.\" Copyright (c) 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Michael Rendell.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\"
.\"     @(#)col.1	8.1 (Berkeley) 6/29/93
.\" $FreeBSD: src/usr.bin/col/col.1,v 1.19 2005/02/13 22:25:20 ru Exp $
.\"
.Dd August 4, 2004
.Dt COL 1
.Os
.Sh NAME
.Nm col
.Nd filter reverse line feeds from input
.Sh SYNOPSIS
.Nm
.Op Fl bfhpx
.Op Fl l Ar num
.Sh DESCRIPTION
The
.Nm
utility filters out reverse (and half reverse) line feeds so that the output is
in the correct order with only forward and half forward line
feeds, and replaces white-space characters with tabs where possible.
This can be useful in processing the output of
.Xr nroff 1
and
.Xr tbl 1 .
.Pp
The
.Nm
utility reads from the standard input and writes to the standard output.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl b
Do not output any backspaces, printing only the last character
written to each column position.
.It Fl f
Forward half line feeds are permitted (``fine'' mode).
Normally characters printed on a half line boundary are printed
on the following line.
.It Fl h
Do not output multiple spaces instead of tabs (default).
.It Fl l Ar num
Buffer at least
.Ar num
lines in memory.
By default, 128 lines are buffered.
.It Fl p
Force unknown control sequences to be passed through unchanged.
Normally,
.Nm
will filter out any control sequences from the input other than those
recognized and interpreted by itself, which are listed below.
.It Fl x
Output multiple spaces instead of tabs.
.El
.Pp
The control sequences for carriage motion that
.Nm
understands and their decimal values are listed in the following
table:
.Pp
.Bl -tag -width "carriage return" -compact
.It ESC\-7
reverse line feed (escape then 7)
.It ESC\-8
half reverse line feed (escape then 8)
.It ESC\-9
half forward line feed (escape then 9)
.It backspace
moves back one column (8); ignored in the first column
.It carriage return
(13)
.It newline
forward line feed (10); also does carriage return
.It shift in
shift to normal character set (15)
.It shift out
shift to alternate character set (14)
.It space
moves forward one column (32)
.It tab
moves forward to next tab stop (9)
.It vertical tab
reverse line feed (11)
.El
.Pp
All unrecognized control characters and escape sequences are
discarded.
.Pp
The
.Nm
utility keeps track of the character set as characters are read and makes
sure the character set is correct when they are output.
.Pp
If the input attempts to back up to the last flushed line,
.Nm
will display a warning message.
.Sh ENVIRONMENT
The
.Ev LANG , LC_ALL
and
.Ev LC_CTYPE
environment variables affect the execution of
.Nm
as described in
.Xr environ 7 .
.Sh EXIT STATUS
.Ex -std
.Sh SEE ALSO
.Xr colcrt 1 ,
.Xr expand 1 ,
.Xr nroff 1 ,
.Xr tbl 1
.Sh STANDARDS
The
.Nm
utility conforms to
.St -susv2 .
.Sh HISTORY
A
.Nm
command
appeared in
.At v6 .
